GEEKRIA Compact Keyboard Case, Vegan Leather Travel Case with Phone and Tablet Holder, Keyboard Case Compatible with Magic Keyboard, Logitech K380/Pebble Keys 2 K380s (Dark Grey)

The foam pad keeps it from dropping between your legs. It also doesn't weigh very much so can keep on your lap for long periods, and it will fit in most backpacks. I am considering other options but this works for the moment. Maybe somebody makes a very light folding board. Here is the folding stand in the photo : https://www.amazon.com/dp/B0D9JPTNVK

So your keyboard doesn't lock? I have been considering this use case and settled on a foam kneepad as a good support for lap editing. This is with a Keychron B1P-K1 keyboard (which I really like) and a keyboard/device stand that is fairly lightweight. This would work with the BYOK. Here is the stand link : www.amazon.com/dp/B0D9JPTNVK